Iron cupferronate

The name cupferron was assigned to the compound by O. Baudisch, and is derived from the fact that the reagent precipitates both copper and iron. Cupferron precipitates iron completely in strong mineral-acid solution, and copper is only quantitatively precipitated in faintly acid solution. The selectivity of the reagent is greatest in strongly acid solution. 

Iron(III) complexes, tetraphenylporphyrinatobenzene-thiolatobenzenethiol-, 517 Iron(IV) complexes phosphines SHAB theory, 1040 Iron cupferronate structure, 510 Iron methoxide physical properties, 346 Iron pivalate basic, 303 Iron proteins iron-sulfur group, 773 Isobacteriochlorins, 851 Isobutyric acid, hydroxy-metal complexes IR spectra, 470 Isobutyric acid, 2-hydroxy-metal complexes NMR, 467 Isocitric acid... 

Cupferron (iron analysis) dissolve 6 g of ammonium nitrosophenyl-hydroxylamine (cupferron) in water and dilute to 100 mL. This solution is stable for about one week if protected from light. 

The cupferron method is very satisfadory for the separation of iron, titanium, zirconium, vanadium and, in spedal cases, tin, tantalum, uranium, and gallium. 

Determination of uranium with cupferron Discussion. Cupferron does not react with uranium(VI), but uranium(IV) is quantitatively precipitated. These facts are utilised in the separation of iron, vanadium, titanium, and zirconium from uranium(VI). After precipitation of these elements in acid solution with cupferron, the uranium in the filtrate is reduced to uranium(IV) by means of a Jones reductor and then precipitated with cupferron (thus separating it from aluminium, chromium, manganese, zinc, and phosphate). Ignition of the uranium(IV) cupferron complex affords U308. 

Molybdenum(VI), vanadium(V), mercury, and iron interfere permanganates, if present, may be removed by boiling with a little ethanol. If the ratio of vanadium to chromium does not exceed 10 1, nearly correct results may be obtained by allowing the solution to stand for 10-15 minutes after the addition of the reagent, since the vanadium-diphenylcarbazide colour fades fairly rapidly. Vanadate can be separated from chromate by adding oxine to the solution and extracting at a pH of about 4 with chloroform chromate remains in the aqueous solution. Vanadium as well as iron can be precipitated in acid solution with cupferron and thus separated from chromium (III). 

The substance is dissolved in ether and by passing in dry ammonia gas the ammonium salt is precipitated. From this salt the iron and copper salts, insoluble in water, are prepared by precipitation with Fe+ + + and Cu++ ( Cupferron ). 

Cupferron (29), as the name suggests, has been applied to the analytical determination of copper and iron. In neutral solution, a white 1 1 complex with Ag1 has been obtained which reacted with Mel to give the methyl ether.292 Reaction of the related ligand (30) with silver nitrate in aqueous methanol gave a red predpitate which on further reaction with Mel gave the methyl ether in a reaction analogous to that for cupferron.293... 

Complexes of neocupferron, the ammonium salt of Ar-nitroso-Ar-2-naphthylhydroxylamine (16 Ar = naphthyl) are less soluble and bulkier than those of cupferron and can be used to determine copper and iron from the sea and natural waters without a preliminary concentration stage. 

Soon after the introduction of dimethylglyoxime as a specific reagent for nickel by Tschugaeff-Kraut-Brunck (1905-1907), Baudisch discovered a compound which precipitates copper and iron quantitatively from acid solutions.82 He appropriately named this reagent as cupferron . It is the water soluble ammonium salt of nitrosophenylhydroxylamine (5). When dissolved in chloroform, the whitish-grey copper compound gives a bright yellow solution and the brown yellow iron(III) compound a deep red solution. This behaviour reveals the inner complex character of these derivatives (6). 

The earliest expectations of cupferron being a selective and specific reagent for copper and iron only were not justified as the reagent has been found to precipitate, with the exception of aluminum and chromium,83 almost all the tri- to penta-valent metals which form insoluble hydrous oxides. However, the reagent has acquired permanent value as an aid in separating certain metals, e.g. titanium from aluminum and chromium.84... 

Of the above derivatives, the ammonium salt of 1-nitrosonaphthylhydroxylamine (12, named as neocupferron) appears to have attracted maximum attention.87 Its uranium, neodymium and cadmium salts (in contrast to the corresponding cupferron precipitates) are soluble in organic liquids. Neocupferron also appears to give a more voluminous (discernable quantity) precipitate with small amounts of iron. 

The composition of iron(III) cupferronate in chloroform was determined photometrically at 325 and 385 nm by the molar ratio methods.101 At both wavelengths the composition of the complex was found to be Fe(PhN202)3. The crystal structure of the complex was determined by three-dimensional Fourier and least-square methods.102 The crystals are monoclinic with a = 12.50, b = 17.45, c = 11.15 A, / = 122° 19 and z = 4 the space group is F2X /a. The cupferron groups are unsymmet-rically attached to iron and are, therefore, crystallographically independent. The Fe—O bond seems to be ionic. 

Iron in the concentration range of the order of 3.5 x 10 4 to 7 x 10-4M can be determined by high-frequency titration in the presence of other metal ions in Fe3+/Ti4+ = 1 and Fe3+/Zr4+ = 1. Total concentration of the two cations can be determined by high-frequency titration with cupferron, followed by a redetermination after masking the interfering ions. 

Figure 11.1 presents a scheme for the radioanalytical determination of 55Fe in water, biota, and sediment samples.11 This procedure is based on the separation of Fe from other metals (especially Cd, Cs, Cu, Ni, and Zn) on an anion exchange resin. The iron is then purified by coprecipitation with cupferron (the ammonium salt of nitrosophenylhydroxylamine). 

A colorimetric method has also been devised which is not interfered with by silicic acid. Iron, however, should be removed by means of cupferron. The solution should contain 0-002 to 0-025 milligram of P2Os and 2 c.c. of nitric acid (density 1-12). To this is added 2 c.c. of a quinine solution made by dissolving 1 gram of the sulphate in a slight excess of nitric add and adding enough baryta to precipitate all the sulphate. The colour developed after the addition of the molybdate is compared with that of a standard.3... 

Cupferron reagent fiocculent yellow precipitate of the titanium salt, Ti(C6H502N2)4, in acid solution (distinction from aluminium and beryllium). If iron is present, it can be removed by precipitation with ammonia and ammonium sulphide solutions in the presence of a tartrate the titanium may then be precipitated from the acidified solution by cupferron. 

Cupferron or amino nitroso phenyl hydroxylamine 1 may be used for the direct precipitation of iron in acid solution, in the presence of aluminium, chromium, cobalt, nickel, and zinc. Copper is precipitated along with the iron, but is easily removed afterwards by treatment with ammonia, m which it is soluble. 

Separation of iron ( Fe) with cupferron complex, and nickel ( Ni) with dimethylglyoxime complex (DMG)2Ni... 

There are many other iron complexes of a similar nature yet to be investigated including many model complexes such as cupferron and ferric acetyl acetonate as well as the hydroxamates and the catechols. 

Estimation.2 — Titanium is determined gravimetrically as TiOi. It is precipitated as the hydroxide with ammonia or by hydrolysis of the salts or precipitation may be accomplished with cupferron after removing iron.1... 

White to light buff crystals sensitive to light, mp 125- 26 with decompn. Soluble in water, methanol insol in ether. The aq soln is unstable. use Reagent for iron and copper. See also Cupferron. 

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